The DNS root zone consists of pointers to the authoritative domain name servers for all TLDs (top-level domains). The root zone is hosted on a collection of root servers operated by several organizations around the world that all use a specific, approved list of domains that is managed by ICANN. By contrast, alternative roots typically include pointers to all of the TLD servers for domains delegated by ICANN, as well as name servers for other, custom top-level domains that are not sanctioned by ICANN. Some alternate roots are operated by the organizations that manage these alternative TLDs.

Alternative DNS roots may be characterized broadly as those run for idealistic or ideological reasons, run as profit-making enterprises, and those run internally by an organization for its own use.[citation needed]. During the dot-com boom, some alternate root providers[who?] believed that there were substantial profits to be made from providing alternative top-level domains.[citation needed] Some of the Internet community have seen alternative DNS roots as beneficial to the Internet, and have run them in protest of centralized DNS control. Zach Bastick proposes that alternative DNS roots have allowed for more democratic control of the Internet:[2]

"The implementation of alternative gTLDs predates any significant debate on name space extension by official actors, and this exemplifies how democratising the DNS alters the pace of developing Internet policy, the nature of decisions that justify that policy development, and political dynamics and user autonomy in the network infrastructure." (p.103)

While technically trivial to set up, the maintenance of a reliable root server network is a serious undertaking.[citation needed] In order for the system to be effective, multiple servers must be run continuously without interruption in geographically diverse locations. Only a small portion of Internet service providers actually use any of the domains served by alternate root operators, generally supporting only ICANN-sanctioned root servers. This has led to the commercial failure of several alternative DNS root providers.[citation needed]

A top-level domain with the name biz, created by Pacific Root, was in operation before ICANN approved the official domain biz, operated by Neulevel. For some time after the creation of the official domain, several alternate roots continued to resolve the name to Pacific Root's servers rather than Neulevel's. Therefore, some domain names existed in different roots and pointed to different IP addresses. The possibility of such conflicts, and their potential for destabilizing the Internet, is the main source of controversy surrounding alternate roots. Many of the alternate roots[who?] try to coordinate with each other, but many do not, and no conflict resolution processes exist among them.

Namecoin top-level domains are not managed by any single organization. Every Namecoin peer has a database copy. Forced work is used to prevent squatting and other kinds of abuse. Namecoin software allows domain registration under any top-level domain, but only .bit top-level domain is currently supported. Users may either use alternative DNS, DNS suffix, gateway, browser plugin or install Namecoin software and gain independent authentic view of namespace. In the latter case, Namecoin domains can't be disabled or transferred by an authority.

Emercoin is a cryptocurrency that also has built-in support for DNS, providing a framework to store and maintain key->value pairs in its decentralized database. Emercoin DNS can support virtually any DNS zone however to prevent collisions with existing DNS zones, two main zones are supported: *.emc and *.coin. Each instance of the Emercoin software contains a simple built-in DNS server supporting the standard RFC 1034 DNS protocol. It is thereby possible to integrate Emercoin DNS into a regular DNS tree via a DNS proxy or full service DNS server.

Name.Space was founded in 1996 and is a supplemental root that resolves the legacy root managed by ICANN as well as hundreds of other top-level domains. Name.Space used crowd sourcing to originate zones based on user demand.[3] Some of the zones managed by Name.Space include: .art, .books, .chat, .design, .film, .green, .help, .inc, .law, .music, .news, .press, .radio, .shop, .talk, .union, .video, .world, and .zone.[4]

micro— micronations and their entities. Recent and not widely used yet.

neo— emo subculture with influences of technology, music, and other forms of multimedia.

null— miscellaneous non-commercial individual sites.

oss— open-source software.

oz— Australian-related content, without the residency requirements of .au.

parody— venue for non-commercial parody work. Having a TLD designated to works of parody attempts to remove claims that a website could be mistaken for a business site, and thus reduces the possibility of claims of trademark infringement.

pirate— created as a reaction against internet censorship. (Currently unavailable due to hardware fault)

Open Root Server Network (ORSN) is a mirror of the ICANN root; terminated 31 December 2008. Restarted on June 2013. It offers the possibility to buy and maintain alternative TLD on specific geographic spaces, at an accessible price. Supported by Louis Pouzin, one of the grandfathers of the internet.

eDNS (Enhanced Domain Name Service) was founded by a coalition of ISPs led by Karl Denninger of the Chicago-area MCSNet.[5][6] It ceased operation in 1998. It served the following domains: biz (general business use), corp (corporations), fam (for and about family), k12 (for and about children), npo (non-profit organizations), per (personal domains), web (web-based sites, Web pages).

New.net was enabled via a DNS hijacker application, usually bundled with legitimate software. The top-level domains New.net provided include: .agent, .arts, .auction, .chat, .church, .club, .family, .free, .game, .golf, .inc, .law, .llc, .llp, .love, .ltd, .med, .mp3, .school, .scifi, .shop, .soc, .sport, .tech, and .video. At one point it offered .travel, .kids, and .xxx but those were removed when they conflicted with domains proposed to ICANN in the first round of creation of new domain names in the primary root since the early history of the DNS. Alternate access to domains registered under New.net's alternative TLDs is provided by third level domains under the new.net domain name space (e.g., example.shop is really example.shop.new.net). As of early 2012, New.net seems to have ceased operation, as the web site "new.net" is no longer resolving.

One of the notable challengers to ICANN's control of the DNS namespace was Open RSC, a group that grew out of private discussions and developed into a public mailing list. It grew large enough that the group decided to submit an application to the United States government to run the DNS.[7]

The organization posted bylaws and articles of incorporation outlining ORSC's position following extensive public discussion regarding the manner in which the DNS was operated.[8][9]

ICANN chairwoman Esther Dyson acknowledged adopting features such as membership from ORSC in her response to the United States Department of Commerce.[10]

ORSC publishes a root zone containing additional top level domains not found in the official root zone.